A hot fairing structure for a pre-diffuser includes a ring-strut-ring structure that comprises a multiple of hollow struts; and a multiple of diffusion passage ducts attached to the ring-strut-ring structure. A pre-diffuser for a gas turbine engine includes an exit guide vane ring having a multiple of exit guide vanes defined around an engine longitudinal axis; a ring-strut-ring structure adjacent to the exit guide vane ring to form a multiple of diffusion passages defined around the engine longitudinal axis, an inlet to each of the multiple of diffusion passages smaller than an exit from each of the multiple diffusion passage through the ring-strut-ring structure; a diffusion passage duct attached to the ring-strut-ring structure at the exit from each of the multiple diffusion passage.
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1. A pre-diffuser downstream of a compressor section of a gas turbine engine, comprising:
a multiple of diffusion passage ducts manufactured of sheet metal;
a full ring ring-strut-ring structure that comprises a multiple of diffusion passages that each communicate with one of the multiple of diffusion passage ducts to extend the diffusion passage of the ring-strut-ring structure downstream along a respective flow passage, each diffusion passage in the ring-strut-ring structure comprises a diffusion passage inlet and a diffusion passage exit adjacent to a respective one of the multiple of diffusion passage ducts welded to the ring-strut-ring structure;
an exit guide vane ring upstream of the ring-strut-ring structure, the exit guide vane ring comprises a multiple of upstream exit guide vanes (EGVs) that split the flow into two adjacent diffusion passage inlets;
a multiple of hollow struts of the full ring ring-strut-ring structure, each of the multiple of hollow struts align with a respective one of the multiple of upstream exit guide vanes, each of the multiple of hollow struts comprises a cavity in communication with a diffuser side of the pre-diffuser through a passage to permit diffusion air from the diffuser side of the pre-diffuser to be received into the respective cavity wherein the passage has a passage opening located on a downstream surface of each of the multiple of hollow struts, and the passage opening is the only inlet or outlet to the cavity for fluidic contact with air outside the cavity.
3. A pre-diffuser for a gas turbine engine, comprising:
an exit guide vane ring having a multiple of exit guide vanes defined around an engine longitudinal axis;
a full ring ring-strut-ring structure adjacent to the exit guide vane ring to form a multiple of diffusion passages defined around the engine longitudinal axis, an inlet to each of the multiple of diffusion passages smaller than an exit from each of the multiple diffusion passage through the ring-strut-ring structure;
a diffusion passage duct attached to the ring-strut-ring structure at the exit from each of the multiple of diffusion passages, the diffusion passage duct manufactured of sheet metal and welded to the ring-strut-ring structure;
an outer radial interface between a radial outer surface of a ring-strut-ring structure and the exit guide vane ring, the outer radial interface being a full hoop structure; and
an anti-rotation feature between the ring-strut-ring structure and the exit guide vane ring, the anti-rotation features inboard of the multiple of diffusion passages;
a hot fairing radial flange that extends radially inward from the ring-strut-ring structure and an exit guide vane radial flange that extends radially inward from the exit guide vane ring;
a static structure flange that abuts the hot fairing radial flange;
a clamp ring that abuts the exit guide vane radial flange;
a multiple of fasteners that fasten the clamp ring to the static structure flange; and
a multiple of hollow struts of the full ring ring-strut-ring structure, each of the multiple of hollow struts align with a respective one of the multiple of upstream exit guide vanes, each of the multiple of hollow struts comprises a cavity in communication with a diffuser side of the pre-diffuser through a passage to permit diffusion air from the diffuser side of the pre-diffuser to be received into the respective cavity, wherein the passage has a passage opening located on a downstream surface of each of the multiple of hollow struts, and the passage opening is the only inlet or outlet to the cavity for fluidic contact with air outside the cavity.
2. The pre-diffuser as recited in
4. The pre-diffuser as recited in
5. The pre-diffuser as recited in
an exit guide vane radial flange 152 that extends transversely from the exit guide vane ring;
a full ring hot fairing radial flange 150 that extends transversely from the ring-strut-ring structure parallel to the exit guide vane radial flange of the exit guide vane ring.
6. The pre-diffuser as recited in
7. The pre-diffuser as recited in
8. The pre-diffuser as recited in
9. The pre-diffuser as recited in
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The present disclosure relates to a gas turbine engine and, more particularly, to a pre-diffuser therefor.
Gas turbine engines include a compressor section to pressurize a supply of air, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. The compressor section discharges air into a pre-diffuser upstream of the combustion section. The pre-diffuser converts a portion of dynamic pressure to static pressure. A diffuser receives the air from the pre-diffuser and supplies the compressed core flow around an aerodynamically-shaped cowl of the combustion chamber. The core flow is typically separating into three branches. One branch is the cowl passage to supply air to fuel nozzles and for dome cooling. The other branches are annular outer plenum and inner plenums where air is introduced into the combustor for cooling and to complete the combustion process. A further portion of the air may be utilized for turbine cooling.
The pre-diffuser is exposed to large thermal gradients and requires various features for anti-rotation, axial retention, and centrality with respect to the central engine axis. These features may result in local discontinuities which may generate stress risers and consequently reduced operational life.
A hot fairing structure for a pre-diffuser according to one disclosed non-limiting embodiment of the present disclosure includes a ring-strut-ring structure that comprises a multiple of hollow struts; and a multiple of diffusion passage ducts attached to the ring-strut-ring structure.
A further aspect of the present disclosure includes that the hot fairing structure is a cast full ring structure.
A further aspect of the present disclosure includes that the multiple of diffusion passage ducts are manufactured of sheet metal.
A further aspect of the present disclosure includes that the multiple of diffusion passage ducts are welded to the ring-strut-ring structure.
A further aspect of the present disclosure includes that each of the multiple of hollow struts include a cavity.
A further aspect of the present disclosure includes a passage in communication with each cavity.
A further aspect of the present disclosure includes that an inlet to each of the multiple of diffusion passages are smaller than an exit from the diffusion passage through the ring-strut-ring structure.
A further aspect of the present disclosure includes that each of the multiple of hollow struts align with one of a respective multiple of exit guide vanes of an exit guide vane ring.
A further aspect of the present disclosure includes a full ring hot fairing radial flange that extends transverse to the multiple of diffusion passages.
A further aspect of the present disclosure includes a first anti-rotation feature on one side of the full ring hot fairing radial flange and a second anti-rotation feature on an opposite side of the full ring hot fairing radial flange.
A further aspect of the present disclosure includes that the first anti-rotation feature engages an exit guide vane ring.
A further aspect of the present disclosure includes that the second anti-rotation feature engages a static structure.
A pre-diffuser for a gas turbine engine according to one disclosed non-limiting embodiment of the present disclosure includes an exit guide vane ring having a multiple of exit guide vanes defined around an engine longitudinal axis; a ring-strut-ring structure adjacent to the exit guide vane ring to form a multiple of diffusion passages defined around the engine longitudinal axis, an inlet to each of the multiple of diffusion passages smaller than an exit from each of the multiple diffusion passage through the ring-strut-ring structure; a diffusion passage duct attached to the ring-strut-ring structure at the exit from each of the multiple diffusion passage.
A further aspect of the present disclosure includes that the hot fairing structure is a cast full ring structure.
A further aspect of the present disclosure includes that the multiple of diffusion passage ducts are manufactured of sheet metal.
A further aspect of the present disclosure includes that the multiple of diffusion passage ducts are welded to the ring-strut-ring structure.
A further aspect of the present disclosure includes an outer radial interface between a radial outer surface of the hot fairing structure and the exit guide vane ring, the outer radial interface being a full hoop structure; and an anti-rotation feature between the hot fairing structure and the exit guide vane ring, the anti-rotation features inboard of the multiple of diffusion passages.
A further aspect of the present disclosure includes comprising a hot fairing radial flange that extends radially inward from the hot fairing structure and an exit guide vane radial flange that extends radially inward from the exit guide vane ring, the seal located between the exit guide vane radial flange and the hot fairing radial flange.
A further aspect of the present disclosure includes a static structure flange that abuts the hot fairing radial flange; a clamp ring that abuts the exit guide vane radial flange; and a multiple of fasteners that fasten the clamp ring to the static structure flange.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation of the invention will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:
The engine 20 generally includes a low spool 30 and a high spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine case structure 36 via several bearing structures 38. The low spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor (LPC) 44 and a low pressure turbine (LPT) 46. The inner shaft 40 drives the fan 42 directly or through a geared architecture 48 to drive the fan 42 at a lower speed than the low spool 30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.
The high spool 32 includes an outer shaft 50 that interconnects a high pressure compressor (HPC) 52 and high pressure turbine (HPT) 54. A combustor 56 is arranged between the HPC 52 and the HPT 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes. Core airflow is compressed by the low pressure compressor 44, then the high pressure compressor 52, mixed with the fuel and burned in the combustor 56, then expanded over the HPT 54 and LPT 46. The HPT 54 and LPT 46 rotationally drive the respective high spool 32 and low spool 30 in response to the expansion.
With reference to
The liners 60, 62 contain the combustion products for direction toward the turbine section 28. Each liner 60, 62 generally includes a respective support shell 68, 70 which supports one or more heat shields 72, 74 that are attached thereto with fasteners 75.
The combustor 56 also includes a forward assembly 80 downstream of the compressor section 24 to receive compressed airflow through a pre-diffuser 100 into the combustor section 26. The pre-diffuser 100 includes a hot fairing structure 102 and an exit guide vane ring 104. The exit guide vane ring 104 includes a row of Exit Guide Vanes (EGVs) 108 downstream of the HPC 52. The EGVs 108 are static engine components which direct core airflow from the HPC 52 between outboard and inboard walls 110 and 112.
The pre-diffuser 100 is secured to a static structure 106 to at least partially form the diffuser module between the compressor section 24 and the combustor section 26. The hot fairing structure 102 is exposed to large thermal gradients and directs the core airflow while forming a shell within the relatively colder static structure 106. The static structure 106 is thereby segregated from the core airflow and generally operates at a relatively lower temperature than the hot fairing structure 102. The hot fairing structure 102 and the exit guide vane ring 104 are full ring structures that are assembled in a manner that allows common thermal growth yet still remain centered with respect to the static structure 106 along the engine central longitudinal axis A.
With reference to
The hot fairing structure 102 and the exit guide vane ring 104 include an anti-rotation interface 130 that positions the anti-rotation features 132, 134 in a region of low stress inboard of the diffusion passages 120. In the disclosed embodiment, the hot fairing structure 102 may include a multiple of circumferentially located anti-rotation tabs 132 (
An axial extension 140 of the hot fairing structure 102 extends along an inner diameter flow surface of the flow passage P. The axial extension 140 at least partially overlaps a recessed area 142 of the exit guide vane ring 104. That is, the axial extension 140 extends in a direction opposite that of the core flow in the flow passage P and overlaps the recessed area 142 (
A hot fairing radial flange 150 extends from the hot fairing structure 102 parallel to an exit guide vane radial flange 152 of the exit guide vane ring 104. A static structure flange 154 extends radially outwardly from the static structure 106 with respect to the engine axis A to abut the hot fairing radial flange 150. That is, the static structure flange 154 operates as a mount location for the hot fairing structure 102 and the exit guide vane ring 104. The hot fairing radial flange 150 also includes a multiple of circumferentially located anti-rotation tabs 156 (
A clamp ring 160 abuts the exit guide vane radial flange 152 to sandwich a seal member 170 between the exit guide vane radial flange 152 and the hot fairing radial flange 150. A seal member 170, e.g., a torsional spring seal, dogbone, or diamond seal, that accommodates compression of the hot fairing structure 102 and the exit guide vane ring 104 in response to axial assembly of the static structure modules. A multiple of circumferentially arranged fasteners 180 fastens the clamp ring 160 to the static structure 106.
An outer radial interface 190 between the hot fairing structure 102 and the exit guide vane ring 104 includes a radial interface 192 and an axial interface 194. Since the outer radial interface 190 of the hot fairing structure 102 and the exit guide vane ring 104 are devoid of discontinuities and are uniform in cross-section around the circumference of the full hoop structures, service life is significantly increased. The anti-rotation interface 130 and the outer radial interface 190 are essentially hidden from the gas path and are located in low stress regions.
With reference to
With reference to
Each passage 202 is located along an axis D and is in communication with the cavity 204 in the hollow strut 200. The passage 202 may be reinforced and permits diffusion air from the diffuser side of the pre-diffuser 100, i.e., the air around the combustor 56, to be received into the respective cavity 204. The diffuser air facilitates thermal control of the ring-strut-ring structure 118 of the hot fairing structure 102 to reduce the mass of the ring-strut-ring structure 118. The reduced mass of the ring-strut-ring structure 118 of the hot fairing structure 102 results in a more responsive thermal characteristic. The strut geometry maximizes the perimeter of the ring-strut-ring structure 118 that is engaged in torsional stiffness. That is, the mass close to the centroid 206 has little to no effect on stiffness. To resist multi-node sinusoidal waves travelling around the circumference of the hot fairing structure 102, local torsional sectional properties of the ring-strut-ring structure 118 facilitate control of the natural frequencies of the hot fairing structure 102.
The ring-strut-ring structure 118 with the hollow regions with the core breakout located close to the centroid 206 of the torsional section forms a pre-diffuser 100 that can have both high natural frequencies and more uniform transient thermal gradients which enables a lightweight, high performance low thermal stress design. The hot fairing structure 102 with a hollow leading edge region and the core opening on the aft side of the hollow strut 200, is located about the mid-axis of the airfoil shape to connect outer diameter static structure, with minimal thermal mass, and an inner diameter static structure with distributed mass such that the transient thermal response is optimized to reduce thermal stress.
The ring-strut-ring structure 118 also allows coupled Exit Guide Vanes with the floating hot fairing to provide improved cyclic life. Light weight tubular flowpath extensions reduce the overall weight of the design, simplify the ring-strut-ring structure 118 casting process, and increase the natural frequencies of the hot fairing by minimizing the cantilevered mass of the tubes. Additionally, the torsionally stiff ring-strut-ring structure 118 ensures that the design can be incorporated with features on the inner diameter structure which facilitates attachment to other structures with the least amount of contact, yet have sufficient frequency margin with respect to engine operating vibration sources.
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the figures or all of the portions schematically shown in the figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.
The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.
McCaffrey, Michael G., Hough, Matthew Andrew, Rivero, Pedro
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